What Causes Nausea Along With Indigestion And Lower Abdominal Discomfort?

Good afternoon. For the last 3 weeks I have had horrible nausea, indigestion, lower abdominal/back discomfort, bloating, and fatigue. I had a very wierd period on the 24th of August, for two days. I have not ever had a period this short in the 12 years of me having had one. I m not going on 4 weeks of having felt this way. I went to urgent care on the 28th they did a pregnancy test which was negative but they also said it could be too early to tell w a pee test. They also said it could be my gallbladder. (Beyond me how both could correlate but obviously I m not a Dr.) He told me to see my PCP if the symptoms persist after a week and to do a blood panel. With this back ground what I m asking is if there a possibility I m pregnant or something else could be wrong? Thanks for your time. -Kay